Notify "storms"

[Todd]

Good day all,

We've run into a problem with our DNS servers.  The way we update our
masters is via a CVS Checkout and reload of the zones modified.
Sometimes though, we need to reload the whole config for big
changs/etc.  When that happens, all 6 masters (I know, we're getting
rid of some) send notifies to all 80+ (I know, we're getting rid of
some) slaves for all 1800 zones.  This causes all the slaves to verify
all 1800 zones on 6 masters, which then delays the changes we made
from actually getting to the slaves.  Right now it's about 2.5 hours
for all slaves to do all zones.

We would like to make this better.  We're trying to figure out what
mechanism might be limiting the rate at which the slave does SOA
checks against the master so it can perform that step quicker.  We
have looked at the zone transfer limits on the master/slave, but that
is related to the transfer mechanism, not the SOA query.

Can anyone help with ideas on this?  Are we missing something obvious?

Cheers,

Todd.